132 



MORPHOLOGY 



8. PiTFALi, Flowers. — These flowers form, as it 

 were, a trap or pit, in which insect visitors are im- 

 prisoned for a period and then set free after pollina- 

 tion has been secured. In isher-mul (fig. ii6) and 

 allied species the simple perianth {p) is inflated below 

 in the form of a jug {t), and con- 

 tracted above into a narrow mouth 

 with the single limb long, dilated, 

 and oblique; the flowers are dis- 

 tinctly protogynous. The inner 

 surface of the limb and the mouth 

 of the jug-shaped perianth or trap 

 are beset with oblique downwardly- 

 directed hairs, which allow small 

 flies or midges which visit them to 

 glide easily into the inflated peri- 

 anth, enclosing the anthers and 

 stigmas at its bottom. If the flower 

 happens to be a young one, the 

 stigmas {st) are mature but not the 

 anthers (a), and the insects (?) are 

 kept imprisoned till the anthers ma- 

 ture, dehisce, and shed their pollen- 

 grains. The pollen-covered insect^ 

 then easily glide out of their prison, 

 as the hairs which had hitherto pre- 

 vented their egress dry up and make 

 their escape easy. If the pollen-covered insects 

 happen next to visit a young flower, the pollen-grains 

 which they carry pollinate the receptive stigma of the 

 latter. The plant, however, is not satisfied with merely 

 having its own stigma pollinated: it keeps the insects 

 imprisoned till its stigmas dry up and anthers mature 

 and dehisce, so that the insects on their escape may 

 carry the pollinating powder to other flowers. The 



Fig:. ii6. — Isher-mul 

 {Aristolochia indicd) 



o. Ovary, a, Anther^ 

 st. Stigma. t. Trap. 

 /, Insect, f. Perianth. 



